GRB 241209D: Swift detection of a burst

At 10:59:46 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 241209D (trigger=1273106). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 190.111, -2.879 which is RA(J2000) = 12h 40m 27s Dec(J2000) = -02d 52' 42" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex structure with a duration of about 150 sec. The peak count rate was ~3200 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 11:01:20.0 UT, 93.6 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 190.1129, -2.8901 which is equivalent to: RA(J2000) = 12h 40m 27.09s Dec(J2000) = -02d 53' 24.5" with an uncertainty of 5.0 arcseconds (radius, 90% containment). This location is 41 arcseconds from the BAT onboard position, within the BAT error circle. No event data are yet available to determine the column density using X-ray spectroscopy. The initial visibility window of the GRB was very short and no prompt UVOT data were generated. We await the full dataset to search for any UV/optical afterglow. Burst Advocate for this burst is T. M. Parsotan (tyler.parsotan AT nasa.gov). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/)